1. Field of the Invention
This invention relates to punches used in reciprocating presses and, more particularly, to punches capable of multiple functions including scarfing and piercing.
2. Description of the Prior Art
Punches used in reciprocating presses are known in the art for piercing openings in materials. The pierced openings may be positioned and shaped by selection of punch cross-section and location with respect to the material. In most instances, the material to be pierced is flat and lays nested in a lower die section of the reciprocating press. The punch is carried in an upper die section and reciprocated thereby upon cycling of the press. Attempts to create openings in flanges or ribbed portions of the material which extend beyond the general plane thereof which may not be nested against a lower die section result in distortions of the material surrounding the opening. In the context of producing openings in vinyl siding this situation is manifested as follows; when installed on the periphery of a building vertically sequential siding members are interlocked to provide a continuous barrier by cooperating flanges. That is, one flange protrudes outwardly from the plane of a first siding member while another flange protrudes inwardly from the plane of a second siding member for respective cooperating engagement therebetween. In a typical siding system, the outwardly protruding flange is located on the top of a siding member and formed as a loop whereas the inwardly protruding member is located on the bottom and formed as a J. In this manner vertically sequential siding members are engaged with one another by cooperating top and bottom flanges. Horizontally abutting siding members must overlap and thereby nest with one another at end portions thereof. Overlapping of end portions is facilitated by trimming and/or notching the top and bottom flanges. Such trimming and/or notching may be performed at the same time the sections are cut to length. That is, a reciprocating press shears a continuously formed structure into individual siding members with a single reciprocating blade and at the same time, the end portions of the top flanges are removed with a two stage shearing operation. The first stage of the shearing operation removes a square portion of the flange leaving a half section of the loop which extends out over a portion of the siding member. The second stage of the shearing operation removes the half section of the loop. The first and second stage shearing operations are performed by shearing blades carried by a common reciprocating member. The first stage of the shearing operation is performed by a blade which is received within a cooperating opening in the lower die. The edge of the opening in the lower die functions as a blade to effect shearing of the siding member therealong. In addition, the opening provides a conduit for scrap conveyance. The second stage shearing operation is performed by a reciprocating blade which is advanced in a manner so as to cut through the loop portion of the top flange and stop immediately prior to contacting the surface of the siding member. As there is no die opening for the half section of the loop to exit the cutting operation, it becomes a nuisance. It may become engaged with moving portions of the equipment resulting in inference therewith. In addition, it it is conveyed with a siding member into a packaging container, it may be concealed within stacks thereof and produce an impression in the respectively engaged siding surfaces resulting in the necessity to scrap the respectively impressed siding members. Therefore, there is a need for a shearing operation which successfully conveys scrap into known collection points as well as pierces openings without distorting the adjacent material.